Throttle body spacers?

Hi to all, I've been researching throttle body spacers because it looks like a fairly easy bolt on component. But I can't figure out if they're just a gimmick or if they actually add more HP. Anyone ever tried putting one on? Or know someone who has? Thanks

You know, I wondered the same thing. From what I hear you do gain a little hp and mileage but hardly noticeable. Then again, some people claim that they notice it, but for the most part people say not to waste your money. But, if you do decide that you want one, make sure you get the helix-bore you don't get that whistling noise. Hope this helps!The Trans-dapt one is the most popular of the people I asked. Also that particular version doesn't get that whistling sound. Unless, you are wanting the whistle. Hope this helps.

From what I understand, the only motors that throttle body spacers make a difference on are the TBI motors. I think this is because it's a vertical style induction system rather than horizontal. Also because the injectors are inside the TB and the stock configuration doesn't allow the cylinders to pull from both, just one. Where as some of the aftermarket one turns that TB into one piece that allows any cylinder to pull from both injectors at the same time making injector matching (which is supposed to be horrible on the TBI motors) less of an issue.

I put one on my old 94 with a 5.7 TBI. It improved throttle response quite a bit, and picked up 1.5-2 MPGs. I don't know how well it would work on a CPI or port injection, as the point of entry is not where air/fuel are mixed.

On a TBI it should work just like a carb spacer or a taller manifold. IIRC it widens the power band as well as smoothing the intake flow, could be wrong about that though. I've done it on my carb'd camaros and gotten throttle response and mpg increases as well as a better seat of the pants feel. And since a TBI is really not much more than a glorified electronic carb (works on the same downdraft principles), you should have roughly the same effect. But if you have a TPI or any MPFI you are better served getting a bigger bore throttle body with a smoother intake to make the power.